Fix all doctest errors

Refs #20185

docs/source/algorithms/PoldiMerge-v1.rst

@@ -67,7 +67,7 @@ This small usage example merges two compatible POLDI-files which have been loade
     total_summed = SumSpectra(spectra_summed)
 
     print("6903+6904 contains a total of {} counts.".format(int(total_summed.dataY(0)[0])))
-    print "Summing the counts of the single data files leads to {} counts.".format(counts_6903 + counts_6904))
+    print("Summing the counts of the single data files leads to {} counts.".format(counts_6903 + counts_6904))
 
 Output:
 

docs/source/algorithms/PolynomialCorrection-v1.rst

@@ -59,7 +59,7 @@ Usage
    data_ws = PolynomialCorrection(data_ws, coefficients, Operation="Multiply")
 
    print("First 5 y values: {}".format(data_ws.readY(0)[0:5]))
-   print "First 5 error values: {}".format(data_ws.readE(0)[0:5]))
+   print("First 5 error values: {}".format(data_ws.readE(0)[0:5]))
 
 .. testoutput::
 

docs/source/algorithms/Power-v1.rst

@@ -38,7 +38,7 @@ Usage
    result_ws = Power(data_ws, 2)
 
    print("Squared values of first spectrum: {}".format(result_ws.readY(0)))
-   print "Squared values of second spectrum: {}".format(result_ws.readY(1)))
+   print("Squared values of second spectrum: {}".format(result_ws.readY(1)))
 
 Output: